My lawn has been infested with a tough crabgrass, up to 50% in some areas....
My lawn has been infested with a tough crabgrass, up to 50% in some areas. Now, in October, it pulls out easily by hand in large clumps, unlike ordinary crabgrass? Nothing else grows in these dense clumps. Is this Japanese stilt grass or something else? How do I control it? Pull it out? It produces prolific amounts of seed.
From the small area in your photo that shows some close-up of the grass, we can see stilt grass. Yes, this in a non-native invasive plant. It is an annual, with very little root system which is easy to pull. Like all invasive plants, it is an opportunist and when fescue lawns are thinning or struggling with difficult weather conditions (we just had an 8 week drought), it will move in to any bare soil.
Stilt grass can be managed somewhat by applying a pre-emergent crabgrass herbicide in the spring. See the publication on our website: http://www.mdturfcouncil.org/admin/uploadfiles/tt-43e-crab.doc
Stilt grass germinates about a week before crabgrass, so the pre-emergent should be applied about a week earlier than usual.
Stilt grass does produce a lot of seed, and if you want to do so, you can pull it before the seed falls. However, you need to get some fescue seeded in those spots right away, or they will just fill with weeds again.